Various multiphase pump types allow compression of a two-phase mixture. However, rotodynamic type machines are limited to GLR ratios hardly higher than 20, and positive-displacement machines are relatively bulky for compression of a wet gas.
It is difficult to use conventional, centrifugal or axial gas compressors to compress a gaseous fluid comprising a liquid phase because of the erosion due to the liquid droplets on the blades of the impellers, of the embrittlement of the blades and of the rotor unbalance resulting therefrom.
A first primary separation stage (working under the action of the terrestrial gravity) is therefore more generally used upstream from a gas compressor for rough separation of the gas and of the liquid, then a second, secondary (for example sieve) separation stage is used for finer separation of the droplets contained in the gas. This layout also requires a single-phase pump for transfer of the liquid from the input pressure to the discharge pressure. These equipments are heavy and bulky.
The volume of the static separators can be reduced while maintaining the same degree of separation of the liquid droplets and of the gas, by generating high centrifugal forces produced only by means of the energy of the fluid (without external energy supply). This is, for example, the working principle of cyclone separators.
The volume of the separators can be reduced further yet, while maintaining the same degree of separation of the liquid droplets and of the gas, by generating very high centrifugal forces produced from an external energy (separator referred to as dynamic separator). It is for example the working principle of the dynamic separator described in the Bertin patent WO-87/03,051. While this separator has the advantage of being relatively compact, it constitutes a second rotating machine when mounted outside the compressor, and it reduces the number of impellers of the compressor by about 30% when mounted inside the compressor.